SystemComPlusPackage

//This trick enables you to share a dword value between:
// 1) All user-mode processes.
// 2) User-mode and Kernel-Mode.
#include "stdafx.h"
#include "windows.h"
#include "stdio.h"

#define SystemComPlusPackage 0x3B


extern "C"
{
    int __stdcall ZwSetSystemInformation(unsigned long  SystemInformationClass,
                                         unsigned long* SystemInformation,
                                         unsigned long  SystemInformationLength);
}

int main(int argc, char* argv[])
{
    unsigned long i=0;
    printf("Enter the value you want to share with all processes ");
    scanf("%d",&i);
    if(i)
    {
        ZwSetSystemInformation(SystemComPlusPackage,&i,0x4);
        void* SharedUserData=(void*)0x7FFE02E0;
        unsigned long SharedValue=*(unsigned long*)((unsigned char*)SharedUserData);
        printf("Shared value is %d\r\n",SharedValue);
        printf("You can ensure that by checking value at address 0x7FFE02E0 in user-mode\r\nand at address 0xFFDF02E0 in kernel-mode\r\n");
    }
    return 0;
}